For the first time we are going to have to hire a babysitter for my 2 kids. We have tickets to a concert & both sets of parents will be out of town. The girl we have asked is on my daughter's swim team & we kinda know her parents. I am definitely comfortable with her watching my kids ages 4 & 8. What is a going rate for a babysitter these days? She is 15 years old and we live in Michigan if that matters? Thanks!